1. Field of the Invention
The present invention relates to an ultrasound endoscope, and relates to an ultrasound endoscope capable of performing both endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) and endoscopic retrograde cholangiopancreatography (ERCP).
2. Description of the Related Art
Conventionally, endoscopes are widely used for various inspections and treatments inside a subject.
In recent years, ultrasound endoscopes that allow endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) to be performed by inserting a needle from a digestive tract for pathological examination using ultrasound images and extracting cells, or endoscopes for performing endoscopic retrograde cholangiopancreatography (ERCP) that inserts a fine tube into a pancreatic duct or bile duct, injects a contrast medium and examines a change in the pancreatic duct or bile duct while checking the tube position by radiography are being developed and commercialized.
In the case of the ultrasound endoscope used for endoscopic ultrasound-guided fine needle aspiration (hereinafter referred to as “EUS-FNA”), since a raising angle of a treatment instrument protruding from a distal end portion of an insertion portion is less than 90 degrees with respect to an insertion axis direction of the insertion portion, it is difficult for an operator to perform endoscopic retrograde cholangiopancreatography (hereinafter referred to as “ERCP”) using an EUS-FNA ultrasound endoscope. For this reason, for example, when the operator inserts an EUS-FNA-enabled ultrasound endoscope into the stomach and observes the pancreas or the like while watching at the ultrasound image, if a lesioned part is discovered in the pancreas or the like from the ultrasound image and endoscopic retrograde cholangiopancreatography (ERCP) needs to be performed, the operator pulls out the ultrasound endoscope from the subject, and inserts an ERCP endoscope into the subject to perform ERCP. That is, the ultrasound endoscope is switched over to the ERCP endoscope.
In the ERCP endoscope, the raising angle of a treatment instrument is, for example, 90 degrees or more. This is because when inserting the treatment instrument such as cannula into the duodenal papilla in ERCP, the treatment instrument needs to protrude from the distal end portion of the insertion portion at an angle of 90 degrees or more with respect to the axial direction of the insertion portion.
During operation, the operation of switching the ultrasound endoscope over to the ERCP endoscope is complicated and also time-consuming. Therefore, to enable one ultrasound endoscope to perform treatments of both EUS-FNA and ERCP, an ultrasound endoscope may be considered which has a structure that allows the raising angle of the treatment instrument to be increased. However, since a puncture needle used during EUS-FNA is rigid, if the operator considerably bends the puncture needle beyond a certain limit, the needle itself may be broken or a bending tendency may be formed on the needle making it impossible to pull out the needle, and it is thereby not possible to increase the raising angle of the treatment instrument of the ultrasound endoscope.
Thus, as disclosed in U.S. Patent Publication No. 6338717, an ultrasound endoscope is proposed which includes a channel that allows both an EUS-FNA treatment instrument and an ERCP treatment instrument to be inserted thereinto and two raising stands for raising the respective treatment instruments.